How to install Sensei theme
Thanks to Duarte Farrahota Ramos for the answer.

Instructions and file to download are here: Sensei 


Download the file sensei_theme_update_10_21_2013.zip
Extract the zip file.
Open Blender and go to “File” at the top choose “User Preferences” and then choose the tab “Themes”
At the bottom of that screen choose “Install Theme” and select the file you just downloaded on your computer.
If you’re happy with the theme changes then go to “File” at the top and select “Save Startup File” and you’re done.


Notes:
(2) Make sure the extract results in an .XML file. 
(5) This doesn't appear to be necessary.